Some RF receivers operate by rapidly switching the center RF frequency being received and processed. One method of operation for these receivers includes periodically changing the RF frequency of the receiver's local oscillator between or among the frequencies required to cause the receiver to sequentially receive and process the several desired receive frequencies. The sequentially changing RF frequencies of the local oscillator are able to be modeled as interleaved bursts of RF frequency signals with alternating RF frequencies at each of the sequential local oscillator frequencies.
Each of these RF bursts can then be thought of as time division multiplexed into a composite, multi-frequency local oscillator signal of a receiver. Receivers that abruptly activate or change local oscillator frequencies essentially create a local oscillator output burst with a square shaped amplitude envelope. Such a square shaped amplitude envelope causes the local oscillator output to have a frequency domain spectrum that corresponds to the well-known SINC function, which is defined by the equation sin(f)/f, centered around each of the local oscillator center frequencies. The SINC function spectrum of this local oscillator output is able to introduce new, undesired, local oscillator spurs as a result of the periodic local oscillator frequency changing. These spurs for square wave local oscillator time domain envelopes can reach −13 dBc and introduce potential receiver interference opportunities as these spurs will also mix in the receiver's mixer with receive signals removed in frequency from the desired signal and be down-converted to the same intermediate frequency.
Therefore a need exists to overcome the problems with the prior art as discussed above.